This invention relates to an electrical component for use in a variable resistor, a band selector or the like having a rotary member. More particularly, the present invention relates to an electrical components having such a rotary member which can be assembled in a holder more simply.
The miniaturization of electrical components has become necessary in recent years in all fileds, and the tuner of a television receiver is no exception. In the tuner of this kind, a large number of band slection switches and a variable resistor for tuning must be fitted into a single frame. If the size of each component is reduced, the production and assembly becomes complicated, and quality control of the component must be extremely strict.
To cope with this problem, an electrical component which is easy to assemble and product has been proposed, as shown in FIGS. 1 and 2. The electrical component consists of a holder 1 having a plurality of holes 1a for receiving the shafts of respective rotary members 2 rotatably so that they may not be removed from the holder. The method of forming this component comprises clamping the holder 1 provided with the holes 1a between first and second molding dies 3 and 4 in close contact therewith as shown in FIG. 2, packing a thermoplastic synthetic resin material into the cavities of these dies 3 and 4 and curing the resin material so as to form the rotary members 2 in place within the holes 1a of the holder 1. Since the rotary members 2 shrink during cooling and curing, a gap occurs between them and the holes 1a of the holder 1 so that the rotary members are rotatable within the holder 1 but held to the holder by a shaft portion 2a that is tapered so as to correspond to the tapered hole 1a. This method can eliminate the necessity of assembling a plurality of rotary members 2 into the holder 1 one by one and can simplify assembly and production.
Even though the electrical component is thus improved, it has a construction which permits a plurality of rotary members 2 to rotate in independent directions after the component is assembled. When a knob (not shown) and a slider receptaacle (not shown) are fitted onto an operating portion 2b and a driving portion 2c, respectively, of each rotary member 2 when the electrical component is used as a band selector switch, for example, the orientations of the knob and the slider receptacle must be located so as to correspond to the rotational orientation of each rotary member 2 and this is extremely troublesome and difficult to automate.